Formation of hydrates is a well known problem in subsea production systems for oil and gas. Several options are available to solve this problem. Traditionally, chemicals have been used. Recently a more effective direct electric heating (DEH) method is used for heating of the pipeline by forcing a high electric current through the pipeline itself. In any form of electrical heating of pipelines a source of electrical power supplying at least a few hundred kilowatts is normally needed. The power often needs to be applied in a programmed sequence to achieve selected operating conditions. Conversion of power from three-phase to single-phase is often necessary, especially in subsea pipeline applications, where power is taken from an existing three-phase power grid. What is needed is an efficient, versatile power supply system that can supply these needs.